rear differential issues

Discussion in '2005+ Mustang GT 4.6L Tech' started by Dale Shoop, Jun 22, 2022.

  1. Dale Shoop

    Dale Shoop Junior Member

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    I purchased and installed a Ford Performance Finned Differential Cover to help keep things cool. I used the gasket from Yukon Gear recommended by American Muscle. I noticed a couple of things that seemed odd: (1) it took way more gear oil than I anticipated. I was expecting a little over two quarts. It took 7! Where did it go? It's not all over the floor of the garage. (2) when I torqued the bolts down, they started to feel like they were going to strip, so I didn't get all the way down to 33 ft pounds. Maybe I should have stopped at 25? I read differing opinions. It does have a very slight drip starting to form, so I'm questioning the gasket and the torque on the bolts.
     
  2. 07 Boss

    07 Boss Senior Member

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    7 qts? How far did you fill it up? There is a plug on the drivers side up closer to the front that you fill it up to. Once it starts flowing out of that your done. How did you know when it was full? Did you fill it up all the way to the fill hole?
     
  3. Dale Shoop

    Dale Shoop Junior Member

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    Screenshot_20220622-124630_Chrome.jpg The new cover came with a fill hole on the back. I filled it to the bottom of that hole.

    Screenshot_20220622-124630_Chrome.jpg
     
  4. 07 Boss

    07 Boss Senior Member

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    Uhhhh... that is way overfilled. Your oil level should be about centerline with your axels. Have you driven the car? I suppose it would start spewing oil out the vent and other places when it gets up to temp.

    Empty and start over. Or just undo the fill plug on the differential itself and let it drain till nothing else comes out though this is still a tad overfilled. You should be able to stick a finger inside the hole and feel oil. It should be within 1/2' of the hole.
     
    808muscle likes this.
  5. 07 Boss

    07 Boss Senior Member

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    Actually thinking about it, you should empty it and start over. I would ditch the gasket and just use a good bead of rtv. I can't remember the last time I actually used a diff cover gasket.
     
  6. Juice

    Juice forum member

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    Pull the plug in the front of the diff, with pan under it. Let it derain. When it stops, you are done.
    Plug is on the driver's side. 3/8" square drive.
     
  7. Forty61

    Forty61 forum member

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    What’s that top plug for if it’s not the fill plug? Breather/catch can? I’d probably have ended up doing the same thing just looking at that without comparing it to the factory one.
     
  8. Juice

    Juice forum member

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    Plugs on the cover can be used for oil cooler.
    You can fill through the top, but only to the level of the front plug.
     
  9. Dale Shoop

    Dale Shoop Junior Member

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    Thanks! This is good info. Wish they came with instructions, but I usually learn best from mistakes anyway. Thoughts on how much torque on the cover bolts? I've read 33 and 25 ft-lbs
     
  10. Juice

    Juice forum member

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    Diff cover bolt torque:
    No more than a 1/4 turn after it bottoms and start to feel resistance. This is not a critical part. Torque wrench not required.
     
    RED09GT likes this.
  11. Daniel Roberson

    Daniel Roberson Member

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    Those do look cool. Are they that visible to the people behind you?
     
  12. Dale Shoop

    Dale Shoop Junior Member

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    No. My car sits too low.
     
  13. Daniel Roberson

    Daniel Roberson Member

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    So what advantage do you get with it? I'm not a mechanic.
     
  14. bambam 06

    bambam 06 Member

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  15. pass1over

    pass1over I like it LOW

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    The fins on the cover help to cool the rear differential fluid.
     
  16. Daniel Roberson

    Daniel Roberson Member

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    Meaning more times down the race track?
     
  17. Dale Shoop

    Dale Shoop Junior Member

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    -yes! I spent the day on the road course at Dominion Raceway and things got too hot.
     
  18. BaddAsp

    BaddAsp Junior Member

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    It will NOT stop leaking best advice remove the cover and gasket use permatex gasket maker with no gasket to seal it
     
  19. RED09GT

    RED09GT Equal Opportunity Offender S197 Team Member

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    I have read good things about the Lube Locker gasket but I'd rather just get the tube of black out of the tool box. It's worked for me with 8.8's since the early 90's.
     
    Mustang Terlingua likes this.
  20. Midlife Crises

    Midlife Crises Senior Member

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    I use the stock Ford gasket. Dry and clean the bolts are tightened to spec using a torque wrench in a cross cross pattern. The cover does not leak.
     
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